It has been found that a stimulable phosphor may be used in radiation image recording and reproducing system. Specifically, a sheet provided with a layer of stimulable phosphorus (herein referred to as stimulable phosphorus sheet) when first exposed to radiation passing through an object, such as a human body, will provide a radiation image stored thereon. When this image has been exposed to a stimulating ray beam such as a laser beam, this will cause the stimulable phosphorus sheet to emit a light in proportion to stored radiation energy. The light emitted by the stimulable phosphorus sheet, upon stimulation thereof, is photoelectrically detected and converted to an electric image signal, and the radiation image of the object is reproduced by a visible image by use of image signal on a recording medium such as a photographic film. The stimulating of the stimulable sheet by a laser beam is typically done using a raster scanning technique. The slow scan direction transport of the stimulable phosphorus sheet is important to the quality of the generated image. Slow scan velocity must be regulated such that the exposure modulation of the scanning beam does not cause image signal modulation greater than a threshold of visible contrast modulation. Therefore, it is important to provide a well regulated linear motion.
Lead screw mechanisms are commonly used to convert angular velocity to linear motion. Such mechanisms usually employ at least one linear guide rod. Lead screw mechanisms commonly require extreme precision and manufacture and assembly in order to function without sticking, jamming, or causing vibrations in required input torque. Any one of these events may cause observable velocity changes when the lead screw mechanism is used for storage phosphorus raster scanning. In addition, linear guides that are used with the lead screw must be exactly parallel to the lead screw and to each other in order to prevent jamming. Similarly, the bearings attached to the moving stage, which supports the stimulable phosphorus sheet, must be co-linear (at all points) to the guides on which they operate to prevent jamming. For long linear motion, such mechanisms may be beyond the capability of normal manufacturing methods to build, thus requiring time-consuming and expensive adjustments during assembly.
Additionally, the mechanism used to guide the stage can not be too loose, or outside forces such as externally applied shocks, dust on the linear guides, etc., can ruin an image being formed by the raster scanning mechanism. The mechanism guiding the linear motion must be sufficiently rigid so that expected forces do not deflect the moving stage such that artifacts will show in the scanned image.
Applicant has invented an improved precision stage assembly which reduces the required precision and expense of manufacturing while maintaining smooth, rigidly guided linear motion to a stage. The present invention comprises improved mechanisms for coupling the lead screw and the stage, and for coupling the stage and the guide bearings on the linear guide which minimizes jamming and sticking, while preventing deflection of the stage from its path by normal forces experienced during operation, such as shocks and contamination of the guide rails.